# Tuning Rashba spin-orbit coupling at LaAlO3/SrTiO3 interfaces by band filling

## TL;DR

This study demonstrates that the Rashba spin-orbit coupling at LaAlO3/SrTiO3 interfaces can be effectively tuned via back-gating, with maximum effects near the Lifshitz transition, relevant for spintronic applications.

## Contribution

It provides experimental evidence linking the Rashba effect to band filling and Lifshitz transition, clarifying gate dependence discrepancies in previous studies.

## Key findings

- Maximum spin-orbit coupling occurs near the Lifshitz point.
- Multiple Lifshitz transitions observed with gate tuning.
- Strong evidence for a single spin winding at the Fermi surface.

## Abstract

The electric-field tunable Rashba spin-orbit coupling at the LaAlO3/SrTiO3 interface shows potential applications in spintronic devices. However, different gate dependence of the coupling strength has been reported in experiments. On the theoretical side, it has been predicted that the largest Rashba effect appears at the crossing point of the $d_{xy}$ and $d_{xz,yz}$ bands. In this work, we study the tuneability of the Rashba effect in LaAlO3/SrTiO3 by means of back-gating. The Lifshitz transition was crossed multiple times by tuning the gate voltage so that the Fermi energy is tuned to approach or depart from the band crossing. By analyzing the weak antilocalization behavior in the magnetoresistance, we find that the maximum spin-orbit coupling effect occurs when the Fermi energy is near the Lifshitz point. Moreover, we find strong evidence for a single spin winding at the Fermi surface.